Made a deposit to the Play William Hill Vegas offer through TrialPay (of 10 euro) and I made at least 10 bets, after which the tank coins that I should have been awarded have not come through. Could I please get any advice on what to do in this situation? The offer was for 450 tank coins.

The free tank coin shit is not trustworthy at all. I remember completing so many surveys/requirements and was only awarded once every dozen trials. You can try waiting a few days if you haven't already.

Would not recommend trying to receive free tank coins as they end up getting different sorts of malware on your computer, and they do not always complete, better to just pay for the tank coins instead of trying to get them for free.

Surely this is a legal issue though, I was essentially told through writing that I would receive something if I paid actual money :/ Is there a way to contact kChamp staff cause that is ridiculous tbh...